Due to the limited supply capacity of a single battery, a plurality of batteries are typically assembled into a battery pack to provide sufficient power when a high power supply is required. However, there is an inevitably difference between parameters such as internal resistances, capacities, self-discharge rates of battery cells in the battery pack due to multiple factors such as a manufacturing accuracy, a process control, etc. This difference will lead to a charging and discharging imbalance of the entire battery pack.
To solve the abovementioned problem, the prior art has provided various solutions. For example, before charging, all the battery cells are discharged to reduce the difference between the battery cells. However, this solution not only leads to complex circuits and higher costs, but also fails to essentially solve the charging and discharging imbalance caused by the difference between parameters of the battery cells.
Therefore, it is necessary to provide a new charging device and system to resolve at least one of the abovementioned problems.